Mechanical interlock for electric circuit

ABSTRACT

A mechanical interlock for components in an electric circuit necessitating a mechanical separation of mating parts which interrupts the electric circuit before access thereto or components thereof is possible, thereby preventing electric shocks to users.

United States Patent 91 Reed [451 Aug. 28, 1973 i 1 MECHANICAL INTERLOCKFOR ELECTRIC CIRCUIT [76] inventor: David M. Reed, PO. Box 652,

Martin, Ky. 41649 [22] Filed: Aug. 16, 1972 [21] Appl. No.: 281,091

[52] US. Cl. 339/75 R, 339/37 [51] Int. Cl H0lr 13/54 [58] Field ofSearch 124/66, 67; 339/36, 339/37, 39, 75, 91, 136, 137

[56] References Cited UNITED STATES PATENTS 1,549,437 8/1925 Bissell339/75 R X 2,384,267 9/1945 Andersen 339/75 R 2,700,141 1/1955 Jones339/75 R X 2,782,391 2/1957 Kirk 339/137 X 3,052,863 9/1962 Uberbacherct a1. 339/136 M X 3,633,150 1/1972 Swartz 339/36 FOREIGN PATENTS ORAPPLICATIONS 695,256 12/1930 France 339/75 P Primary Examiner-Marvin A.Champion Assistant Examiner-Terrell P. Lewis Attorney-David H. Semmes [57 ABSTRACT A mechanical interlock for components in an electric circuitnecessitating a mechanical separation of mating parts which interruptsthe electric circuit before access thereto or components thereof ispossible, thereby preventing electric shocks to users.

9 Claims, 4 Drawing Figures MECHANICAL INTERLOCK FOR ELECTRIC CIRCUITBACKGROUND OF THE INVENTION In numerous applications involving the useof electric circuits for motive power and the like, frequent access tocomponents of the electric circuit for repair, inactivating,disconnection of components and the like are desirable and necessary.One such application is to vehicles such as employed, for example, inmining operations and the like which usually consist of work vehiclesincluding electric batteries for motive power, the batteries havingsubstantial voltage and require frequent servicing or changing of thebatteries, or disconnection of one vehicle component from another. Suchwork vehicles of a mine operations type are shown, for example, in priorU.S. Pats. Nos. 3,226,587 and 3,545,634. Such operations in the absenceof safeguards such as provided in the present invention might subject anoperator or user to contact with a live electric circuit with aconsequent, perhaps fatal, electric shock.

The present invention has as its primary purpose the provision of meansto negate this possibility.

SUMMARY OF THE INVENTION The present invention is for a mechanicalinterlock mechanism for association with an electric circuit whichrequires a mechanical separation of mating mechanical parts which servesto interrupt the electric circuit before access to the circuit orcomponents thereof is possible. Interruption of the electric circuit bya mechanical separation of mechanical components prevents possibleelectric shocks to operators or users.

The present invention is particularly suitable for use with electricpower motivated mining vehicles and the like which require frequentservicing and/or changing of batteries and/or separation of mechanicalcomponents of the vehicles although obviously not limited thereto, theconcept and structure being more broadly applicable.

Additional objects and advantages of the invention will be more readilyapparent from the following detailed description of an embodimentthereof when taken together with the accompanying drawings in which:

FIG. 1 is a perspective view of the mechanical interlock for an electriccircuit in connected or assembled condition;

FIG. 2 is a view similar to FIG. 1 with the components shown inseparated or disconnected condition;

FIG. 3 is a top plan view of the assembled interlock apparatus; and

FIG. 4 is aside elevational view of the structure shown in FIG. 3.

Referring now in greater detail to the drawings, which will be describedwith reference to application of the invention to a mining vehicle orthe like, which is actuated by electric batteries, although theprinciples and structure applicable to other uses, the mechanicalinterlock generally designated 10 is especially adapted forinterconnecting a fuse box and electric circuit as used in anelectrically driven and operated vehicle such as a mining vehicle.Another application of the mechanical interlock would consist of aconnection between, for example, a vehicle control box and theelectrical circuit. In the drawings, the fuse box is generally indicatedat 12 into which electrical leads are appropriately connected throughwire conduit 14, the structure including a packing gland assembly 16, aclamp 18 such as an adjustable screw clamp or the like. The packinggland assembly is connected to fuse box 12 through a gas tight sealindicated at 20. A seal wire 22 of a known type is provided betweenappropriate collars as shown.

The fuse box is provided with a screw threadedly engaged inspection cap24 having indents 26 on the periphery thereof and a removable set screw28 is engageable in the body of the fuse box to prevent rotation of theinspection cap when operatively inserted with respect to the indents onthe inspection cap.

The fuse box has operatively connected thereto a plug generallydesignated 30 adapted for insertion in a cooperating or coactingreceptacle 32 for establishing the electrical connection. The receptaclehas electric leads therefrom through conduit 34 with appropriatesecurement means and seal wire generally designated 36. A receptaclecover 38 encompasses receptacle 32 and is of a generally cylindricalconfiguration from which a receptacle cover handle 40 extends which isof an elongate design and from which a receptacle cover flange dependsand constitutes an end for the receptacle cover. The flange is adaptedfor mating engagement with an apertured cover plate 44 and secured bymeans of hex bolt, lock washer combinations as indicated at 46, the plug30 being insertable therethrough into operative engagement in receptacle32. When disengaged, as shown in FIG. 2, a closure cap 48 suspended bymeans of chain 50 can be screw threadedly engaged on mating threadsprovided on closure cap 48 as shown. The free end of handle 40terminates in an apertured flat lug 52.

Fuse box 12 has an interlock gland ring 54 mounted on fuse box extension56, the ring having a lug and set screw 58 for securement on thethreaded end of plug 30. A cap 60 is also adapted for screw threadedengagement on the cover as shown in FIG. 3.

A locking stem and holder 62 includes a hold down flange 64 at an endthereof engageable and connected to inspection cap 24 through the mediumof hold down washer 66 and hex bolts and lock washers 68 and seal wire70. The opposite end of the locking stem holder is provided with a slot72 adapted for mating reception of apertured flat lug 52 throughlongitudinal sliding engagement therein when the receptacle and plug arebrought into mating engagement for interconnecting and activating theelectrical circuit. The assembled relationship is shown in FIG. 1 of thedrawings. A lock 74 is operatively engageable in the aperture 76 in flatlug 52. In order to make or break the connection between plug andreceptacle, it is necessary to slidably engage flat lug 52 in andthrough the slot 72 in the locking stem 62. The inspection cap 24 cannotbe removed prior to disengagement of the receptacle cover handle and thelocking stem holder to free the inspection cap for removal. The matinglug and slot, in conjunction with the lock, prevent such a disconnectionand provide for safety of personnel handling the apparatus. An aperturedear or lug 78 is provided on receptacle cover 38 and can be used forsecurement of cap 48 and in assembled relationship of the parts.

It will accordingly be seen that a longitudinal sliding movement of theplug and receptacle toward or away from one another is required beforethe parts can be disconnected and prior to access to, for example, thefuse box. The same principle can be applied in different usage areaswith, for example, a control box or the like.

Manifestly, minor changes in the details of construction can be effectedwithout departing from the spirit and scope of the invention as shownand described and as defined and limited solely by the appended claims.

I claim:

1. A mechanical interlock for an electric circuit comprising:

A. a plug connected to a first section of said circuit;

B. a receptacle connected to a second section of said circuit adaptedfor coupling with said plug;

C. a receptacle cover encompassing said receptacle and including:

i. an elongate handle extending longitudinally exteriorly thereof;

D. a locking stern and holder connected to said plug and extendinglongitudinally exteriorly thereof;

E. said handle and said locking stem having coacting and mating free endportions adapted for locking interengagement upon longitudinal movementof said receptacle cover and said plug with respect to one another tolock said plug and said receptacle against displacement anddisengagement.

F. a circuit component compartment connected in said first section, anaccess opening to said compartment, a detachable access cover on saidaccess opening, said locking stem being attached to said access coverand preventing removal thereof when said locking stem and said handleare in locking interengagement.

2. A mechanical interlock as claimed in claim 1, said access cover beingscrew threadedly engaged with said compartment and rotation thereof forremoval being prevented by said attached locking stem.

3. A mechanical interlock as claimed in claim 2, said locking stem beingdetachably connected to said access cover.

4. A mechanical interlock as claimed in claim 1, said locking stemhaving an elongated slot in the free end thereof, said handle having alaterally extended ear thereon, said ear being slidable within said slotupon said longitudinal movement of said receptacle cover and said plugand lockingly interengaging the members.

5. A mechanical interlock as claimed in claim 4, said ear having anaperture therethrough, said aperture being adapted for engagement by aremovable lock.

6. A mechanical interlock as claimed in claim 5, the free end of saidlocking stem having a slotted transversely extending lug, said ear beingslidable through the slot in said lug and prevented from removal when asaid lock is operatively engaged in said aperture in said ear.

7. A mechanical interlock as claimed in claim 6, wherein said componentcompartment comprises a fuse box..

8. A mechanical interlock as claimed in claim 6, wherein said componentcompartment comprises a control box for said circuit.

5. A mechanical interlock as claimed in claim 6, including a removableend cap for said receptacle and screw threadedly engageable therewith.

* i i f

1. A mechanical interlock for an electric circuit comprising: A. a plugconnected to a first section of said circuit; B. a receptacle connecteDto a second section of said circuit adapted for coupling with said plug;C. a receptacle cover encompassing said receptacle and including: i. anelongate handle extending longitudinally exteriorly thereof; D. alocking stem and holder connected to said plug and extendinglongitudinally exteriorly thereof; E. said handle and said locking stemhaving coacting and mating free end portions adapted for lockinginterengagement upon longitudinal movement of said receptacle cover andsaid plug with respect to one another to lock said plug and saidreceptacle against displacement and disengagement. F. a circuitcomponent compartment connected in said first section, an access openingto said compartment, a detachable access cover on said access opening,said locking stem being attached to said access cover and preventingremoval thereof when said locking stem and said handle are in lockinginterengagement.
 2. A mechanical interlock as claimed in claim 1, saidaccess cover being screw threadedly engaged with said compartment androtation thereof for removal being prevented by said attached lockingstem.
 3. A mechanical interlock as claimed in claim 2, said locking stembeing detachably connected to said access cover.
 4. A mechanicalinterlock as claimed in claim 1, said locking stem having an elongatedslot in the free end thereof, said handle having a laterally extendedear thereon, said ear being slidable within said slot upon saidlongitudinal movement of said receptacle cover and said plug andlockingly interengaging the members.
 5. A mechanical interlock asclaimed in claim 4, said ear having an aperture therethrough, saidaperture being adapted for engagement by a removable lock.
 6. Amechanical interlock as claimed in claim 5, the free end of said lockingstem having a slotted transversely extending lug, said ear beingslidable through the slot in said lug and prevented from removal when asaid lock is operatively engaged in said aperture in said ear.
 7. Amechanical interlock as claimed in claim 6, wherein said componentcompartment comprises a fuse box.
 8. A mechanical interlock as claimedin claim 6, wherein said component compartment comprises a control boxfor said circuit.
 9. A mechanical interlock as claimed in claim 6,including a removable end cap for said receptacle and screw threadedlyengageable therewith.